İbrahim Gündoğan

Presence and Distribution of Lithium in Borate Deposits and Some Recent Lake Waters of West-Central Turkey

The presence and distribution of lithium, which is used in a variety of applications in current technology and will be a strategic component in near future technology, has been investigated within the scope of some of Turkeys borate and non-borate Neogene basins and recent lakes. Clay samples from the Turkish borate deposits, Soma lignite basin, and Beypazari trona basin, and water samples from Acigöl, Salda, Yarisçi, Burdur, Egirdir, Tersakan, Bolluk, Karapinar (Acigöl), and Tuzgölü lakes were studied. Analytical results show that the lithium values obtained from clays of borate deposits vary between 0.17 and 0.58% Li2O, and lake water samples contain between 0.30 and 325 mg/l Li+. Lithium is mostly bounded in the clay minerals at the borate deposits. While, the Beypazari trona deposit has lithium between 10 and 46 ppm, the Soma lignite basin does not contain lithium. Therefore, lithium is mainly related to evaporatic formations. These lithium amounts indicate that both the waters of Tuzgölü lake and the clays associated with borate deposits are potential lithium resources, and that they may be considered for economic use in the near future. In western Turkey, geothermal sources mostly depend on the graben faulting system; they also contain minor amounts of lithium.

Sodium sulphate deposits of Neogene age: the Kirmir Formation, Beypazari Basin, Turkey

The Evaporite Member of the Kirmir Formation was deposited in shallow lacustrine environments during the upper Miocene. The most soluble minerals of this member can be currently observed in the Cayirhan mine. The Evaporite Member, which is composed of secondary gypsum at outcrop, can be subdivided into a bedded lower unit and a massive upper unit. In the bedded lower unit, most of the gypsum throughout the basin can be identified as having been transformed from glauberite. In the glauberite layers of the Cayirhan mine, some glauberite textures (‘clear glauberite’) suggest a primary, subaqueous, free precipitation on a depositional floor. More common, however, are the glauberite textures indicating an interstitial growth within a clayey-magnesitic matrix. In the thenardite layers accompanying the glauberite in the Cayirhan mine, some disruption structures can be assigned to synsedimentary dissolution. These structures together with the textures of the thenardite suggest that the original sodium sulphate was mirabilite, thenardite being a secondary phase, which formed during early to moderate burial diagenesis. The massive upper unit, in which evidence of sodium-bearing minerals is absent, is characterized by laminated to banded gypsum and nodular gypsum in the marginal areas of the evaporitic basin, whereas thick, clast-supported gypsum breccias prevail in the northern, deeper part of the basin. The brecciation of these calcium sulphate layers occurred as a result of synsedimentary, gravitative slumping under tectonic control. Although the sulphur isotopic values (d 34 S) of the sulphates of the Kirmir Formation suggest a marine-derived brine supply, the oxygen isotopic values (d 18 O) and the strontium ratios ( 87 Sr/ 86 Sr) do not support such a supply. The origin of the mother brines, the glauberite genesis, the depositional model of the sodium sulphates, and the salinity evolution are discussed. D 2002 Elsevier Science B.V. All rights reserved.

Sedimentological and Petrographical Aspects of Upper Miocene Evaporites in the Beypazari and Çankiri-Çorum Basins, Central Anatolia, Turkey

Upper Miocene evaporites in the Beypazari and Cankiri-Corum basins were deposited in an inter-montane playa–lake complex environment and are intercalated with gypsiferous mudstones and clay-stones. In the Beypazari basin, these evaporites are part of the Kirmir Formation, and in the Çankiri-Çorum basin they occur in the Bozkir Formation. In these two basins, the evaporite minerals comprise mainly Ca-sulfate (gypsum and anhydrite) and Na-sulfate minerals (glauberite and thenardite). The Kirmir Formation consists of a cyclic alternation of gypsiferous claystone, carbonate mud-stone, gypsum-cemented sandstone, alabastrine gypsum rosettes after glauberite, and laminated-banded pseudomorphic alabastrine secondary gypsum after Na-sulfate minerals; at the top, a thick-bedded porphyroblastic secondary gypsum lithofacies is present. The Na-sulfate lithofacies in the Kirmir Formation is dominated by lens-shaped idiomorphic glauberite crystals, which are cemented and/or replaced by thenardite. In the weathering zone of the Na-sulfate deposit, glauberite minerals are transformed to the secondary gypsum that shows a very typical crystalline texture. The main crystalline textures of this secondary gypsum are reticulate, acicular, spindle-shaped acicular, and zigzag textures with acicular crystalline fabric in alabastrine and porphyroblastic secondary gypsum matrix. The Bozkir Formation in the Cankiri-Corum basin comprises, in ascending order, claystone, gypsum-cemented sandstone, laminated to thin-bedded limestone and claystone alternations, nodular alabastrine and porphyroblastic secondary gypsum after anhydrite, laminated secondary gypsum (after gypsarenite?), and thick-bedded alabastrine secondary gypsum after glauberite (at some localities) and claystone alternations, alabastrine micro-nodular secondary gypsum after anhydrite and claystone with displacively grown discoidal gypsum crystal alternation, partly primary and partly secondary gypsum with claystone, and, at the top, selenitic gypsum, a lithofacies of the gypsarenite-gypsiferous claystone alternation. The evaporite sequences of the Bozkir Formation can be divided simply into two parts—a lower part represented by predominantly secondary gypsum and an upper part consisting of mainly primary gypsum (selenites and gypsarenites). Geochemical study of the secondary gypsum after glauberite shows that this type of gypsum has less than 1% Na2O, which is attributed to weathering of the outcrop. Thus, typical secondary gypsum textures after glauberite may be used as a guide in Na sulfate exploration.